16i' Mr. Griffith, on the Order of Succession of the Older 



from two inches to a quarter of an inch in diameter, imbedded 

 in a reddish gray arenaceous base. The conglomerate is suc- 

 ceeded by coarse-grained brownish-red slate, which is occa- 

 sionally quarried and used for inferior roofing slate ; these strata 

 are followed by a series of beds, consisting of red quartzose 

 sandstone alternating with coarse slate, the sandstone beds 

 presenting occasionally a conglomeritic character, but the 

 pebbles rarely exceed half an inch in diameter. The strata 

 dip to the west, though irregularly, at an average angle of 

 about 10° from the horizon; and consequently in ascending 

 the glen in a southern direction, the cliffs present the out- 

 going or strike of the beds, which are not horizontal, but ex- 

 hibit a tortuous arrangement presenting frequent undulations 

 from north to south. At Esknagluggerny, a short distance 

 beyond the southern extremity of Coosane lake, the old red 

 sandstone strata are cut oif by the great north-west and 

 south-east fault already mentioned, immediately to the south 

 of which thick beds of green chloritic quartz rock appear at 

 the surface, dipping to the south at an angle of 30° from the 

 horizon. These strata probably form the lowest portion of 

 the transition rocks situated to the south of Castlemaine Bay, 

 as we perceive the whole series to be complete in an ascending 

 order from them to the summit of the Reeks. 



Commencing then with this chloritic quartz rock base, and 

 proceeding in a southern direction, we find that the same 

 rocks continue to dip to the south, and present an accumu- 

 lation of strata for upwards of 500 feet in thickness, varying 

 little in their composition or character, with the exception of 

 an occasional interstratification of thin beds of green and 

 purplish gray clay slate. These slates are quite distinct in 

 character, as well as in colour and composition, from the 

 coarse red slate of the old red sandstone ; they are in fact 

 identical with the Valentia slates, and bear a strong resem- 

 blance in coloui", composition, and lithological character to 

 some of those of North Wales. Still ascending in the series, 

 we find that the colour of the rocks gradually changes from 

 green to gray, and at length the mineral chlorite is altogether 

 wanting. These gray quartzose beds are not so thick as 

 those which contain chlorite; they likewise alternate with thin 

 beds of clay slate, which present a purplish gray colour, with- 

 out any admixture of green. The gray strata may amount 

 altogether to about 800 feet in thickness. Still continuing to 

 ascend, the same character and alternations are preserved as 

 the last described, but on a fresh fracture the quartzose beds 

 present a slight bloom or tint of red, and the disintegrated 

 surface of the rock exhibits a decidedly reddish hue, which 



